From 5fb985ad2376b7c0d393b195ef5cfa2306ff2345 Mon Sep 17 00:00:00 2001
From: Michael McLoughlin <mmcloughlin@gmail.com>
Date: Tue, 6 Nov 2018 21:10:54 -0500
Subject: [PATCH] sketch

---
 ast.go     | 53 ++++++++++++++++++++++++++++++++++
 printer.go | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 138 insertions(+)
 create mode 100644 ast.go
 create mode 100644 printer.go

diff --git a/ast.go b/ast.go
new file mode 100644
index 0000000..cb1c3f1
--- /dev/null
+++ b/ast.go
@@ -0,0 +1,53 @@
+package avo
+
+// GoType represents a Golang type.
+type GoType interface{}
+
+// Parameter represents a parameter to an assembly function.
+type Parameter struct {
+	Name string
+	Type GoType
+}
+
+// Instruction is a single instruction in a function.
+type Instruction struct {
+	Mnemonic string
+	Operands []string
+}
+
+// File represents an assembly file.
+type File struct {
+	functions []*Function
+}
+
+// Function represents an assembly function.
+type Function struct {
+	name   string
+	params []Parameter
+	inst   []Instruction
+}
+
+func NewFunction(name string) *Function {
+	return &Function{
+		name: name,
+	}
+}
+
+func (f *Function) AddInstruction(i Instruction) {
+	f.inst = append(f.inst, i)
+}
+
+// Name returns the function name.
+func (f *Function) Name() string { return f.name }
+
+// FrameBytes returns the size of the stack frame in bytes.
+func (f *Function) FrameBytes() int {
+	// TODO(mbm): implement
+	return 0
+}
+
+// ArgumentBytes returns the size of the arguments in bytes.
+func (f *Function) ArgumentBytes() int {
+	// TODO(mbm): implement
+	return 0
+}
diff --git a/printer.go b/printer.go
new file mode 100644
index 0000000..19d7158
--- /dev/null
+++ b/printer.go
@@ -0,0 +1,85 @@
+package avo
+
+import (
+	"fmt"
+	"io"
+	"strings"
+)
+
+// dot is the pesky unicode dot used in Go assembly.
+const dot = "\u00b7"
+
+type Printer interface {
+	Print(*File) error
+}
+
+type GoPrinter struct {
+	w         io.Writer
+	by        string // generated by
+	copyright []string
+	err       error
+}
+
+func NewGoPrinter(w io.Writer) *GoPrinter {
+	return &GoPrinter{
+		w:  w,
+		by: "avo",
+	}
+}
+
+func (p *GoPrinter) SetGeneratedBy(by string) {
+	p.by = by
+}
+
+func (p *GoPrinter) Print(f *File) error {
+	p.header()
+
+	for _, fn := range f.functions {
+		p.function(fn)
+	}
+
+	return p.err
+}
+
+func (p *GoPrinter) header() {
+	p.generated()
+	p.nl()
+	p.incl("textflag.h")
+	p.nl()
+}
+
+func (p *GoPrinter) generated() {
+	p.comment(fmt.Sprintf("Code generated by %s. DO NOT EDIT.", p.by))
+}
+
+func (p *GoPrinter) incl(path string) {
+	p.printf("#include \"%s\"\n", path)
+}
+
+func (p *GoPrinter) comment(line string) {
+	p.multicomment([]string{line})
+}
+
+func (p *GoPrinter) multicomment(lines []string) {
+	for _, line := range lines {
+		p.printf("// %s\n", line)
+	}
+}
+
+func (p *GoPrinter) function(f *Function) {
+	p.printf("TEXT %s%s(SB),0,$%d-%d\n", dot, f.Name(), f.FrameBytes(), f.ArgumentBytes())
+
+	for _, i := range f.inst {
+		p.printf("\t%s\t%s\n", i.Mnemonic, strings.Join(i.Operands, ", "))
+	}
+}
+
+func (p *GoPrinter) nl() {
+	p.printf("\n")
+}
+
+func (p *GoPrinter) printf(format string, args ...interface{}) {
+	if _, err := fmt.Fprintf(p.w, format, args...); err != nil {
+		p.err = err
+	}
+}